A production method for a coaxial unit high-speed parallel transmission symmetrical cable

Abstract

The present invention relates to the technical field of cable production, and in particular to a method for producing a coaxial unit high-speed parallel transmission symmetrical cable, the method comprising the following steps: S1: conductor polishing; S2: insulation extrusion or wrapping molding, using a PTFE extrusion cable insulation process or a PTFE microporous tape wrapping cable insulation molding process; S3: shield wrapping, using electronic-grade high-frequency ultra-low profile copper foil (HVLP) for wrapping; S4: shield shaping; S5: inner buffer layer wrapping; S6: filling and cabling, using a 100% back-twisting cage stranding machine for cabling; S7: outer buffer layer wrapping, using the same wrapping method as the inner buffer layer, and completed simultaneously during the filling and cabling processes; S8: braiding; S9: sheath molding. The entire method can reduce damage to the coaxial sub-units during the cabling process, achieve relative fixation of the positions between the coaxial sub-units, and reduce the delay difference between the coaxial sub-units.

Description

Technical Field

[0001] The present invention relates to the technical field of cable production, and in particular to a method for producing a coaxial unit high-speed parallel transmission symmetrical cable. Background Art

[0002] The basic transmission unit structure of high-speed parallel transmission symmetrical cable can be referred to Figure 1 A cross-section of the cable consists of a metal conductor 1, an insulating layer 2, and a metal shield 3. Its structure is characterized by two insulated single wires arranged in parallel and covered with a metal shield. This conforms to the definition of parallel wire pairs in high-speed parallel cables for digital communications as defined in relevant standards. Currently, the high-speed cable structure described above has a maximum mature data transmission bandwidth of 112Gbps per unit at a length of 5 meters. At shorter lengths of 2 or 1 meter, the maximum mature data transmission bandwidth per unit can reach 224Gbps.

[0003] However, for the next generation of higher transmission bandwidth, such as the transmission bandwidth requirement of up to 336Gbps or 448Gbps per unit, this structure can no longer meet the requirements. The reason is that the two insulators are in the same shielding layer, and the external shielding adopts the "wrapping" process method, which tightly wraps the two insulators together, causing the cross-sectional shape of the insulation to deform from the ideal circle to an ellipse, which ultimately leads to uneven distribution of the electromagnetic field between the two conductors, reduced transmission signal quality, and the inability to improve the transmission bandwidth. In addition, since the two conductors of the parallel line share a shielding layer as the conductor of the return current, at high frequencies, due to the skin effect principle, such as Figure 2 As shown, the effective current flow area 4 of the inner conductor (the area covered by the lines) is drastically reduced to 75% of the circumferential area of ​​the inner conductor's outer surface, and 100% of the circumferential area of ​​the inner conductor's outer surface cannot be used. As a result, the effective cross-sectional area of ​​the inner conductor of the parallel pair structure does not reach 100%, which in turn makes the signal loss of the structure relatively large, the signal quality deteriorates relatively seriously, and it is difficult to increase the transmission bandwidth.

[0004] In response to the above problems, the invention patent with authorization announcement number CN221861297U discloses a high-speed Ethernet automotive high-speed data transmission cable, which includes two parallel signal conductors, each of which has an insulating material, a shielding layer and a buffer layer in sequence. The two signal conductors are no longer in the same shielding layer, which reduces signal loss and improves signal quality and transmission bandwidth; however, this parallel transmission symmetrical cable with coaxial units still has certain problems during production: 1) The two transmission sub-units are coaxial structures, and the coaxial sub-units are prone to passive axial torque during the cabling process, causing damage; 2) There are gaps between the coaxial sub-units, which are prone to relative displacement and friction and collision damage, resulting in an uneven outer circular contour after cabling; 3) The physical length of the coaxial sub-units is not easy to maintain consistency, so that there is a delay difference between the coaxial sub-units, affecting the transmission bandwidth of the cable. Summary of the Invention

[0005] The present invention provides a method for producing a coaxial unit high-speed parallel transmission symmetrical cable, which can reduce the damage caused to the coaxial sub-units during the cabling process, realize the relative fixation of the positions between the coaxial sub-units, and reduce the delay difference between the coaxial sub-units.

[0006] To solve the above problems, the present invention provides a method for producing a coaxial unit high-speed parallel transmission symmetrical cable using the following technical solutions:

[0007] A method for producing a coaxial unit high-speed parallel transmission symmetrical cable comprises the following steps:

[0008] S1: Conductor polishing: the surface of the silver-plated copper conductor is polished using a diamond drawing die;

[0009] S2: Insulation extrusion or wrapping molding, using PTFE extrusion cable insulation process or PTFE microporous tape wrapping cable insulation molding process;

[0010] S3: Shielded wrapping, using electronic-grade high-frequency ultra-low-profile copper foil (HVLP) for wrapping, and using a concentric active-release constant-tension wrapping machine for wrapping. During the wrapping process, the insulated core does not rotate, and the copper foil actively rotates and wraps around the surface of the insulated core;

[0011] S4: Shield shaping: With the help of the circular hole mold, the outer diameter of the wrapped copper foil shield semi-finished product is squeezed and reduced by 0.03mm to 0.06mm, so that the contact between the wrapped copper foils is closer, the shape is more rounded, and the outer diameter fluctuation is smaller;

[0012] S5: The inner buffer layer is wrapped using a concentric active tape-releasing constant tension wrapping machine. During the wrapping process, the insulated core does not rotate, and the buffer tape actively rotates and wraps around the surface of the shielded core. The tension during the wrapping process is set at 30% to 70% of the average breaking force of the buffer tape, so that the buffer tape is tightly wrapped around the shielding surface to form good buffer protection;

[0013] S6: Filling and cabling: A 100% back-twist cage stranding machine is used for cabling. At the same time, an appropriate amount of dry cotton yarn is added to the gaps between the coaxial lines of each sub-unit to ensure that the positions of the coaxial sub-units are relatively fixed. During the cabling process, the pay-off tension of each coaxial sub-unit is consistent, and an active pay-off process is used to reduce damage to the coaxial sub-units caused by pulling.

[0014] S7: The outer buffer layer is wrapped in the same way as the inner buffer layer and is completed simultaneously with the filling and cabling process;

[0015] S8: Braiding: evenly braid the tinned or tinned copper-clad aluminum-magnesium alloy wires onto the outside of the semi-finished cable;

[0016] S9: Sheath molding, using polyvinyl chloride or low-smoke halogen-free polyolefin or cross-linked polyolefin, through a tubular extrusion process to form the sheath.

[0017] The above scheme has the following beneficial effects: using refined mirror-finished silver-plated copper as the inner conductor can ensure that under high-frequency conditions, when current flows in the silver layer on the surface of the silver-plated copper due to the skin effect, the resistivity of silver is the lowest, and the surface roughness is low, resulting in a low effective resistance and low signal loss, thereby achieving a higher finished product transmission bandwidth; using low-density microporous PTFE as the insulating dielectric material can ensure that the dielectric loss is the lowest among existing materials, thereby achieving a higher finished product transmission bandwidth; using pure copper foil with extremely low surface roughness as the shielding outer conductor can ensure that under high-frequency conditions, when current flows only on the surface of the copper foil due to the skin effect, the surface effective resistance of the copper foil is low, thereby reducing signal loss; using mature concentric wrapping can achieve an insulation concentricity of more than 96% in batches; a multi-pronged approach can achieve a higher finished product transmission bandwidth;

[0018] A 100% back-twist cage stranding machine is used for cabling. At the same time, an appropriate amount of dry cotton yarn is added to the gaps between the coaxial lines of each sub-unit, so that the coaxial sub-units will not be passively axially twisted and damaged during the cabling process. The appropriate amount of dry cotton yarn can keep the positions of the coaxial sub-units relatively fixed, so that the coaxial sub-units will not easily move and cause friction and collision damage, and the outer circle contour after cabling will be more rounded;

[0019] During the cabling process, the pay-out tension of each coaxial sub-unit is consistent, and an active pay-out process is adopted, which can minimize the damage caused by pulling on the coaxial sub-units, maximize the consistency of the physical length between the coaxial sub-units, and thus reduce the delay difference between the coaxial sub-units, so as to improve the transmission bandwidth of the cable.

[0020] Furthermore, in step S1, the silver-copper surface after polishing reaches the mirror standard, which is that there are no protrusions and dents, no impurities, and the silver layer is continuous without pinholes and copper leakage under a 200x microscope. The surface roughness is not greater than 0.2um, the thickness of the silver layer is not less than 1um, and conductors of different sizes are selected for different specifications, and the fluctuation of the outer diameter of the conductor should be controlled within ±0.001mm.

[0021] Furthermore, in step S2, the outer diameter of the product after molding is 0.03 mm to 0.06 mm larger than the preset outer diameter to leave a margin for subsequent processing, and the fluctuation of the insulation molding outer diameter is controlled within ±0.02 mm.

[0022] Furthermore, in step S3, the tension during the wrapping process is set to 50% to 70% of the average breaking force of the copper foil tape, so that the copper foil tape is tightly wrapped around the insulating surface to form a well-contacted and continuous shielded outer conductor.

[0023] Furthermore, the overlapping coverage of the copper foil is not less than 40% and not more than 49%, and the principle is to make the surface smooth and reduce the gap after the coating is completed. At the same time, the outer diameter fluctuation of the semi-finished product wrapped with copper foil is controlled within ±0.04mm.

[0024] Furthermore, in step S4, while the circular hole mold presses and shrinks the copper foil shielding semi-finished product, the heating temperature of the semi-finished product is gradually increased until the mold is heated to 350°C to 390°C. The high-temperature mold is used to shape the semi-finished product to its size and shape. After shaping, the semi-finished product is quickly cooled to ensure that the shape is cooled and solidified. Nitrogen or other protective gases are used to protect the semi-finished product during the heating process to prevent oxidation of the copper foil.

[0025] The beneficial effects of the above scheme are: the effect of heating and setting is:

[0026] a. The temperature of 350°C to 390°C is higher than the annealing temperature of copper, which is about 270°C. This completes the annealing of the copper foil, reduces the resistivity of the copper foil of the shielding outer conductor, and thus reduces the loss of the shielding outer conductor.

[0027] b. The contact surface of the wrapped and overlapped copper foil produces a welding effect under the action of high temperature and diameter reduction extrusion, further reducing the wrapped and overlapped copper foil shielding outer conductor to form a whole, reducing resistance, and further reducing the loss of the shielding outer conductor.

[0028] c. The temperature of 350℃ to 390℃ can melt the PTFE surface close to the inner surface of the shielded outer conductor copper foil, and bond it to the copper foil to form a stable overall structure.

[0029] d. After cooling, the outer diameter of the wire core is reduced by extrusion, and the density of the molten PTFE on the surface increases due to extrusion, reaching a solid level of about 2.05 g / cm³, which increases the surface hardness and strength of the insulating wire core, improves the insulating wire core's ability to resist extrusion deformation, and makes the insulating wire core less likely to be deformed and damaged in subsequent process operations, ensuring the workability of the insulation.

[0030] Furthermore, in step S5, when the inner buffer layer is wrapped, the shielding rate of the buffer tape on the surface of the shielded wire is not less than 90% and not more than 100%. The principle is to make the surface smooth and the gaps small after the wrapping is completed. The outer diameter fluctuation of the semi-finished product wrapped with the buffer tape meets the requirement of ±0.06mm.

[0031] Furthermore, during filling and cabling, when the number of transmission channels is less than 8, a cabling operation is performed;

[0032] When the number of transmission channels is greater than or equal to 8, the cables of the transmission channels are cabled in two steps. In the first cabling process, the wrapping of the middle 2 pairs of 4 cores and the inner buffer layer is completed. In the second cabling process, the 2 pairs of 4 cores and the inner buffer layer semi-finished products completed in the first cabling are used as the central unit, and together with the remaining 6 pairs of 12-core coaxial sub-units and filling cotton thread, 100% back-twisted cage-twisted cables are performed, and the wrapping of the outer buffer layer is completed at the same time.

[0033] Furthermore, in step S8, the braiding density is not less than 80%, and the tension of the reel and the tension of the braiding wire are controlled during braiding to reduce physical damage to the transmission unit, thereby increasing the transmission bandwidth of the cable.

[0034] Furthermore, before braiding, the semi-finished cable is coated with a layer of aluminum foil to further compensate for the shielding density of the braiding. The aluminum side of the aluminum foil faces outward, and a conductor is added between the aluminum foil and the braided mesh as a ground wire to facilitate the subsequent connection between the cable and the connector. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an illustrative and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0036] Figure 1 It is a structural diagram of a symmetrical cable in the prior art;

[0037] Figure 2A schematic diagram of an effective area for current flow in a symmetrical cable in the prior art;

[0038] Figure 3 Schematic diagram of the structure of the symmetrical cable in the present invention;

[0039] Figure 4 A schematic diagram of the effective area for current flow in a symmetrical cable according to the present invention;

[0040] Figure 5 Schematic diagram of a symmetrical cable with 8 pairs of transmission channels in the present invention;

[0041] Figure 6 This is a flowchart of the method for producing the coaxial unit high-speed parallel transmission symmetrical cable provided by the present invention;

[0042] Description of reference numerals:

[0043] 1. Metal conductor; 2. Insulation layer; 3. Metal shielding layer; 4. Effective area for current flow; 5. Inner buffer layer; 6. Outer buffer layer; 7. Braided wire; 8. Sheath; 9. Filling cotton thread. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0045] Embodiments of the method for producing a coaxial unit high-speed parallel transmission symmetrical cable provided by the present invention:

[0046] like Figure 3 and Figure 4 As shown, compared with the prior art, the symmetrical cables produced by the production method of the coaxial unit high-speed parallel transmission symmetrical cable provided by the present invention each include a metal conductor 1, an insulating layer 2, a metal shielding layer 3 and an inner buffer layer 5, and the high-frequency current generated therefrom flows through the effective area 4, with low signal loss and attenuation, which can effectively improve the transmission bandwidth.

[0047] like Figure 6 As shown, the production method of the coaxial unit high-speed parallel transmission symmetrical cable includes the following steps:

[0048] S1: Conductor polishing: the surface of the silver-plated copper conductor is polished using a diamond drawing die;

[0049] S2: Insulation extrusion or wrapping molding, using PTFE extrusion cable insulation process or PTFE microporous tape wrapping cable insulation molding process;

[0050] S3: Shielded wrapping, using electronic-grade high-frequency ultra-low-profile copper foil (HVLP) for wrapping, and using a concentric active-release constant-tension wrapping machine for wrapping. During the wrapping process, the insulated core does not rotate, and the copper foil actively rotates and wraps around the surface of the insulated core;

[0051] S4: Shield shaping: With the help of the circular hole mold, the outer diameter of the wrapped copper foil shield semi-finished product is squeezed and reduced by 0.03mm to 0.06mm, so that the contact between the wrapped copper foils is closer, the shape is more rounded, and the outer diameter fluctuation is smaller;

[0052] S5: The inner buffer layer is wrapped using a concentric active tape-releasing constant tension wrapping machine. During the wrapping process, the insulated core does not rotate, and the buffer tape actively rotates and wraps around the surface of the shielded core. The tension during the wrapping process is set at 30% to 70% of the average breaking force of the buffer tape, so that the buffer tape is tightly wrapped around the shielding surface to form good buffer protection;

[0053] S6: Filling and cabling: A 100% back-twist cage stranding machine is used for cabling. At the same time, an appropriate amount of dry cotton yarn is added to the gaps between the coaxial lines of each sub-unit to ensure that the positions of the coaxial sub-units are relatively fixed. During the cabling process, the pay-off tension of each coaxial sub-unit is consistent, and an active pay-off process is used to reduce damage to the coaxial sub-units caused by pulling.

[0054] S7: The outer buffer layer is wrapped in the same way as the inner buffer layer and is completed simultaneously with the filling and cabling process;

[0055] S8: Braiding: evenly braid the tinned or tinned copper-clad aluminum-magnesium alloy wires onto the outside of the semi-finished cable;

[0056] S9: Sheath molding, using polyvinyl chloride or low-smoke halogen-free polyolefin or cross-linked polyolefin, through a tubular extrusion process to form the sheath.

[0057] Specifically, in step S1, the silver-copper surface after polishing reaches the mirror standard, which is that there are no protrusions and dents, no impurities, and the silver layer is continuous without pinholes and copper leakage under a 200x microscope. The surface roughness is not greater than 0.2um, the thickness of the silver layer is not less than 1um, and conductors of different sizes are selected for different specifications, and the fluctuation of the outer diameter of the conductor should be controlled within ±0.001mm.

[0058] Using refined mirror-finished silver-plated copper as the inner conductor can ensure that under high-frequency conditions, when the current flows in the silver layer on the surface of the silver-plated copper due to the skin effect, the resistivity of silver is the lowest, and the surface roughness is low, resulting in a low effective resistance, which reduces the signal loss and enables a higher finished product transmission bandwidth.

[0059] In step S2, the outer diameter of the product after molding is 0.03mm to 0.06mm larger than the preset outer diameter to leave a margin for subsequent processing, and the fluctuation of the insulation molding outer diameter is controlled within ±0.02mm.

[0060] In step S3, the tension during the tape wrapping process is set to 50% to 70% of the average breaking force of the copper foil tape, so that the copper foil tape is tightly wrapped around the insulating surface to form a well-contacted and continuous shielded outer conductor.

[0061] At the same time, the overlapping coverage of the copper foil is not less than 40% and not more than 49%. The principle is to make the surface smooth and reduce the gap after the coating is completed. At the same time, the outer diameter fluctuation of the semi-finished product wrapped with copper foil is controlled within ±0.04mm.

[0062] In step S4, while the circular hole mold presses and shrinks the copper foil shielding semi-finished product, the heating temperature of the semi-finished product is gradually increased until the mold is heated to 350°C to 390°C. The high-temperature mold is used to shape the semi-finished product to its size and shape. After shaping, the semi-finished product is quickly cooled to ensure that the shape is cooled and solidified. Nitrogen or other protective gases are used to protect the semi-finished product during the heating process to prevent oxidation of the copper foil.

[0063] The beneficial effects of the above scheme are: the effect of heating and setting is:

[0064] a. The temperature of 350°C to 390°C is higher than the annealing temperature of copper, which is about 270°C. This completes the annealing of the copper foil, reduces the resistivity of the copper foil of the shielding outer conductor, and thus reduces the loss of the shielding outer conductor.

[0065] b. The contact surface of the wrapped and overlapped copper foil produces a welding effect under the action of high temperature and diameter reduction extrusion, further reducing the wrapped and overlapped copper foil shielding outer conductor to form a whole, reducing resistance, and further reducing the loss of the shielding outer conductor.

[0066] c. The temperature of 350℃ to 390℃ can melt the PTFE surface close to the inner surface of the shielded outer conductor copper foil, and bond it to the copper foil to form a stable overall structure.

[0067] d. After cooling, the outer diameter of the wire core is reduced by extrusion, and the density of the molten PTFE on the surface increases due to extrusion, reaching a solid level of about 2.05 g / cm³, which increases the surface hardness and strength of the insulating wire core, improves the insulating wire core's ability to resist extrusion deformation, and makes the insulating wire core less likely to be deformed and damaged in subsequent process operations, ensuring the workability of the insulation.

[0068] In step S5, when the inner buffer layer is wrapped, the shielding rate of the buffer tape on the surface of the shielded wire is not less than 90% and not more than 100%. The principle is to make the surface smooth and the gaps small after the wrapping is completed. The outer diameter fluctuation of the semi-finished product wrapped with the buffer tape meets ±0.06mm.

[0069] During filling and cabling, when the number of transmission channels is less than 8, a cabling operation is performed;

[0070] When the number of transmission channels is greater than or equal to 8, such as Figure 5 As shown, the symmetrical cable includes a metal conductor 1, an insulating layer 2, a metal shielding layer 3, an inner buffer layer 5, a filling cotton thread 9, an outer buffer layer 6, a braided wire 7, and a sheath 8; the cable for the transmission channel is cabled twice, and the first cabling process completes the wrapping of the middle 2 pairs of 4 cores and the inner buffer layer; in the second cabling process, the 2 pairs of 4 cores and the inner buffer layer semi-finished products completed in the first cabling are used as the central unit, and together with the remaining 6 pairs of 12-core coaxial sub-units and the filling cotton thread, 100% back-twisted cage-twisted cabling is carried out, and the wrapping of the outer buffer layer is completed at the same time.

[0071] In order to compensate for the fact that the physical lengths of the two pairs of four-core coaxial sub-units of the central unit and the six pairs of 12-core coaxial sub-units around it are as consistent as possible after the second cabling, it is necessary to appropriately reduce the cabling pitch during the first cabling and appropriately increase the cabling pitch during the second cabling so as to achieve the physical lengths of all coaxial sub-units as consistent as possible, thereby reducing the delay difference between the coaxial sub-units and improving the transmission bandwidth of the cable.

[0072] In step S8, the braiding density is not less than 80%, and the tension of the retracted and released wires and the tension of the braiding wires are controlled during braiding to reduce physical damage to the transmission unit, thereby increasing the transmission bandwidth of the cable.

[0073] Before braiding, the semi-finished cable is covered with a layer of aluminum foil to further compensate for the shielding density of the braiding. The aluminum side of the aluminum foil faces outward, and a conductor is added between the aluminum foil and the braided mesh as a ground wire to facilitate the subsequent connection between the cable and the connector.

[0074] According to the above description of this specification, those skilled in the art may also understand that the terms used below, such as "up", "down", "front", "back", "left", "right", "width", "horizontal", "top", "bottom", "inside", "outside" and other terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the drawings of this specification. They are only for the purpose of facilitating the explanation of the scheme of the present invention and simplifying the description, rather than explicitly or implicitly indicating that the devices or elements involved must have the specific orientation, be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms cannot be understood or interpreted as limitations on the scheme of the present invention.

[0075] In addition, in the description of this specification, “a plurality of” means at least two, for example, two, three or more, etc., unless otherwise clearly and specifically defined.

Claims

1. A method for producing a coaxial unit high-speed parallel transmission symmetrical cable, characterized in that: The steps include: S1: conductor polishing; S2: Insulation pushing or wrapping forming; S3: Shielded wrapping, using electronic-grade high-frequency ultra-low-profile copper foil (HVLP) for wrapping, and using a concentric active-release constant-tension wrapping machine for wrapping. During the wrapping process, the insulated core does not rotate, and the copper foil actively rotates and wraps around the surface of the insulated core; S4: Shield shaping: With the help of the circular hole mold, the outer diameter of the wrapped copper foil shield semi-finished product is squeezed and reduced by 0.03mm to 0.06mm, so that the contact between the wrapped copper foils is closer, the shape is more rounded, and the outer diameter fluctuation is smaller; S5: The inner buffer layer is wrapped using a concentric active tape-releasing constant tension wrapping machine. During the wrapping process, the insulated core does not rotate, and the buffer tape actively rotates and wraps around the surface of the shielded core. The tension during the wrapping process is set at 30% to 70% of the average breaking force of the buffer tape, so that the buffer tape is tightly wrapped around the shielding surface to form good buffer protection; S6: Filling and cabling: A 100% back-twist cage stranding machine is used for cabling. At the same time, an appropriate amount of dry cotton yarn is added to the gaps between the coaxial lines of each sub-unit to ensure that the positions of the coaxial sub-units are relatively fixed. During the cabling process, the pay-off tension of each coaxial sub-unit is consistent, and an active pay-off process is used to reduce damage to the coaxial sub-units caused by pulling. S7: outer buffer layer wrapping; S8: Weaving; S9: Sheath molding.

2. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to claim 1, characterized in that: In step S1, after polishing, the silver-copper surface reaches the mirror standard, which is observed under a 200x microscope to have no protrusions and dents, no impurities, and a continuous silver layer without pinholes or copper leakage. The surface roughness is not greater than 0.2um, the thickness of the silver layer is not less than 1um, and different sizes of conductors are selected for different specifications, and the fluctuation of the outer diameter of the conductor should be controlled within ±0.001mm.

3. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to claim 2, characterized in that: In step S2, the outer diameter of the product after molding is 0.03mm to 0.06mm larger than the preset outer diameter to leave a margin for subsequent processing, and the fluctuation of the insulation molding outer diameter is controlled within ±0.02mm.

4. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to any one of claims 1 to 3, characterized in that: In step S3, the tension during the tape wrapping process is set to 50% to 70% of the average breaking force of the copper foil tape, so that the copper foil tape is tightly wrapped around the insulating surface to form a well-contacted and continuous shielded outer conductor.

5. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to claim 4, characterized in that: The overlapping coverage of the copper foil shall not be less than 40% and not more than 49%. The principle is to make the surface smooth and reduce the gap after the coating is completed. At the same time, the outer diameter fluctuation of the semi-finished product wrapped with copper foil shall be controlled within ±0.04mm.

6. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to any one of claims 1 to 3, characterized in that: In step S4, while the circular hole mold presses and shrinks the copper foil shielding semi-finished product, the heating temperature of the semi-finished product is gradually increased until the mold is heated to 350°C to 390°C. The high-temperature mold is used to shape the semi-finished product to its size and shape. After shaping, the semi-finished product is quickly cooled to ensure that the shape is cooled and solidified. Nitrogen or other protective gases are used to protect the semi-finished product during the heating process to prevent oxidation of the copper foil.

7. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to any one of claims 1 to 3, characterized in that: In step S5, when the inner buffer layer is wrapped, the shielding rate of the buffer tape on the surface of the shielded wire is not less than 90% and not more than 100%. The principle is to make the surface smooth and the gaps small after the wrapping is completed. The outer diameter fluctuation of the semi-finished product wrapped with the buffer tape meets ±0.06mm.

8. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to any one of claims 1 to 3, characterized in that: During filling and cabling, when the number of transmission channels is less than 8, a cabling operation is performed; When the number of transmission channels is greater than or equal to 8, the cables of the transmission channels are cabled in two steps. In the first cabling process, the wrapping of the middle 2 pairs of 4 cores and the inner buffer layer is completed. In the second cabling process, the 2 pairs of 4 cores and the inner buffer layer semi-finished products completed in the first cabling are used as the central unit, and together with the remaining 6 pairs of 12-core coaxial sub-units and filling cotton thread, 100% back-twisted cage-twisted cables are performed, and the wrapping of the outer buffer layer is completed at the same time.

9. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to any one of claims 1 to 3, characterized in that: In step S8, the braiding density is not less than 80%, and the tension of the retracted and released wires and the tension of the braiding wires are controlled during braiding to reduce physical damage to the transmission unit, thereby increasing the transmission bandwidth of the cable.

10. The method for producing a coaxial unit high-speed parallel transmission symmetrical cable according to claim 9, characterized in that: Before braiding, the semi-finished cable is covered with a layer of aluminum foil to further compensate for the shielding density of the braiding. The aluminum side of the aluminum foil faces outward, and a conductor is added between the aluminum foil and the braided mesh as a ground wire to facilitate the subsequent connection between the cable and the connector.

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